Several underlying principles are key to an understanding of the present invention.
It is theoretically possible to pump a volume of fluid such as ambient air into a chamber containing fluid at a second pressure such as a compressed gas chamber with the investment of a certain amount of work which work will be exactly equal to the amount of work which is produced by taking the same volume of fluid and reversing the process, that is, expanding that same quantity of gas from the second pressure to the first pressure.
As is known from thermodynamics, adding heat to the gas such as while it is in the pressurized chamber will produce an increment of increased work during the expansion with the amount of work produced during the expansion being a function of the amount of heat added, the pressure ratio, etc. The difference between the expansion work and the compression work may be used to overcome friction and provide a net work output if desired (expansion work less compression work less friction work). The friction work is the friction force times the distance moved by a mass experiencing that friction force.
From thermodynamics, greater compression ratios and greater heating of the compressed gas lead to better engines measured with respect to work output per unit fuel used, work output per unit weight, work output per unit volume occupied by the engine, etc. Thus, there has been no motivation to make a collapsible engine and more particularly, an engine wherein the heater for the compressed gas comprises a large flaccid walled airtight container.
Rolling diaphragm pumps and expansion motors can be almost frictionless with the friction on the order of 1% of the energy needed to compress a quantity of gas.
The embodiments disclosed herein which are heat engines are most closely related to the Brayton cycle which is more commonly embodied as a gas turbine engine.
The maintenance of life requires certain supplies and conditions such as oxygen, water, food and an acceptable environmental temperature. As is obvious, such supplies and conditions need not be available except locally such as oxygen in air provided to a SCUBA diver for respiration through his mouthpiece or a suitable temperature maintained next to his skin such as may be obtained by the use of a "wet suit".
Mountain climbers climb mountains which are far from sources of resupply so that they must carry supplies with them, such supplies including food, fuel and, during high altitude climbs, bottled oxygen.
The following table suggests the atmospheric pressures (PSIA-lbf/in.sup.2 Absolute) and water boiling points (temperatures) which might be expected at various altitudes:
Pressure Altitude Water Pressure Altitude Water (PSIA) (ft) B.P. (.degree. F.) (PSIA) (ft) B.P. (.degree. F.) 4.5 29,000 157.8 5.0 26,421 162.2 5.5 24,085 166.3 6.0 21,951 170.1 6.5 19,989 173.6 7.0 18,173 176.9 7.5 16,481 179.9 8.0 14,898 182.9 8.5 13,412 185.6 9.0 12,012 188.3 9.5 10,686 190.9 10.0 9,428 193.2 10.5 8,232 195.2 11.0 7,092 11.5 6,001 12.0 4,598 12.5 3,958 13.5 2,071
(Note that daily weather conditions will provide some variation of these values.)